I had adults attempt two different nests. First one was directly above the barn aisle, where I couldn’t do anything about it, and all the babies (not fledglings) all plummeted to their deaths. Second nest was in a better spot and I put a muck bucket with hay under it. It went from four or five happy chirping babies to none overnight it seems. One dead in the bucket, one dead not in the bucket, and one dead hanging from the nest.
I don’t have starlings in the barn, which in the past have killed sparrow babies. What else can it be? Starving to death? Lord knows I have enough adults outside flying around eating bugs. I was very hopeful for the second nest to have success, so that they would come back and nest next year.